In vivo and in vitro immunologic parameters will be measured in a series of patients with carcinoma of the colon. It is anticipated that approximately 300 patients will be tested initially and during the course of their disease for Tumor Associated Antigen levels, lymphocyte cytotoxicity and serum blocking antibodies, lymphoblastogenesis, macrophage inhibition and Rosette formation as well as Dermal antigen response and careful clinical appraisal of their response to surgery, chemotherapy and radiotherapy.